Pre-Lithiated Silicon-Carbon Anodes to Prevent Current Collector Peeling
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Solution Overview
Problem
Conventional non-aqueous electrolyte secondary batteries face challenges in achieving improved battery characteristics and reliability due to issues like degradation, capacity reduction, and adverse effects on current collection performance caused by the expansion and contraction of silicon-based materials during charging and discharging.
Innovation Solution
The development of a non-aqueous electrolyte secondary battery with a negative electrode mixture comprising a carbon-based material and a silicon-based material, where lithium ions are pre-doped through electrochemical treatment, and the use of a higher electrolyte concentration in the negative electrode mixture compared to the electrolytic solution, along with specific materials like lithium hexafluorophosphate and polyvinylidene fluoride, to enhance adhesion and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used in the negative electrode to increase capacity, then battery capacity is improved, but adhesion to the current collector deteriorates due to expansion and contraction during charging and discharging
Solution Approach 1:
The patent applies parameter changes by controlling the potential of the negative electrode at a specific point during deep discharge to be 3.2 V vs (Li/Li+) or less. This potential control parameter ensures that the silicon-based material maintains adequate adhesion to the current collector while still providing high capacity, resolving the contradiction between capacity improvement and adhesion maintenance.
Solution Approach 2:
The patent applies local quality by creating a specific electrolyte concentration distribution where the electrolyte concentration in the negative electrode mixture is higher than in the electrolytic solution excluding the negative electrode mixture. This localized concentration enhancement improves adhesion at the critical electrode-collector interface while maintaining overall battery performance.
2Use of energy by moving object
If silicon-based material is used to expand capacity, then energy storage is improved, but current collection performance deteriorates due to peeling from the current collector
Solution Approach 1:
The patent applies preliminary action by pre-doping lithium ions into the negative electrode active material powder through electrochemical treatment before battery assembly. This preliminary lithium ion incorporation stabilizes the silicon-based material structure, preventing peeling during subsequent charge-discharge cycles and maintaining current collection performance throughout the battery's energy storage function.
Solution Approach 2:
The patent uses parameter changes by specifying that the negative electrode potential at a point during deep discharge must be 3.2 V vs (Li/Li+) or less. This potential parameter control prevents excessive expansion and contraction of the silicon-based material, thereby preventing peeling from the current collector while maintaining high energy storage capacity.
3Reliability
If electrolyte concentration in negative electrode mixture is increased to improve adhesion, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by specifying a potential threshold (3.2 V vs (Li/Li+)) and an electrolyte concentration relationship (concentration in negative electrode mixture > concentration in electrolytic solution excluding negative electrode mixture). These clear parameter specifications provide straightforward manufacturing guidelines that achieve improved adhesion and cycle characteristics without excessive complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively improves the battery's charge and discharge cycle characteristics, reduces adverse effects on current collection, and maintains reliability by compensating for irreversible capacity losses and minimizing peeling from the current collector.
Implementation Method 1
lithium ions are pre-doped through electrochemical treatment
Implementation Method 2
pre-doping lithium ions to the negative electrode active material powder through electrochemical treatment
Implementation Method 3
an electrolytic solution including an electrolyte and a solvent
Implementation Method 4
the expansion and contraction of silicon-based materials during charging and discharging
Data Source
AI summary
A non-aqueous electrolyte secondary battery includes at least a negative electrode including a negative electrode mixture, a positive electrode, and an electrolytic solution including an electrolyte and a solvent. The negative electrode mixture includes a negative electrode active material powder, the negative electrode active material powder includes a carbon-based material and a silicon-based material, a mixing ratio of the carbon-based material to the silicon-based material (carbon-based material (mass %)/silicon-based material (mass %)) is 90 mass %/10 mass % to 0 mass %/100 mass %.